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Sharing geospatial data among agencies is a hot topic in certain government circles. The concept is being pushed by the Office of Management and Budget as an e-government imperative and by the Homeland Security Department to bolster cross- government infrastructure assurance.

In turn, such government interest has encouraged the development of interoperability specifications by organizations such as the OpenGIS Consortium (OGC) Inc. that would allow geographic information systems (GIS) to swap data with one another. OGC is also planning to develop interoperability specifications among the systems and other types of software applications.

For example, the organization recently signed a memorandum of understanding with the International Alliance for Interoperability (IAI) for a joint program to enable the two-way flow of data among computer-aided design and drafting (CADD) systems and various GIS.

Down in the agency trenches, however, this promise of interoperability is still just a dream. The need is immediate, but there's a suspicion that the kinds of standards that OGC and IAI will produce might not be enough to deliver the functionality that users need. For many agencies, the best chance of short-term relief may come in the increasingly common vendor-to-vendor initiatives, designed to address the most pressing interoperability needs.

For example, the Army Corps of Engineers, a large CADD user, works on projects with city, state and county agencies, which often have an existing GIS "with a wealth of data," said Roger Porzig, CADD manager for the corps' Jacksonville District. Corps engineers know they could come up with better decisions if they could get some of that geospatial data into their CADD tools, he said.

"In some cases we get it, but many times it becomes a challenge to match up the data in the design process," Porzig said. "What we need is the ability of engineers working with a CADD program to be able to reach into the enterprise GIS and pull out the information they need, complete with the attribution data."

The kind of specifications and standards that OGC and IAI produce are beneficial, he said. However, a drawback to consensus-based standards efforts is that the results may be incomplete from the users' point of view.

"What we don't need from a field perspective is a low-level, stripped-out, dumbed-down conversion [of data]," Porzig said. "That won't solve the problem."

The kind of functionality he is looking for will more likely come from a one-to-one match of a CADD vendor's system with one from a GIS company.

For example, Bentley Systems Inc., one of the biggest vendors of architecture/engineering/construction (AEC) systems, recently announced a technology project with ESRI, a leading GIS company, that will allow each company's solutions to directly access each other's data. The Army Corps of Engineers uses both companies' tools and stands to benefit from the work.

Bentley also provides OGC-compliant data that can be accessed by other applications through an Oracle Corp. database, said Styli Camateros, vice president of Bentley Geospatial.

"But, by definition, the simple features that can be provided [through OGC compliance] can't include the richness that you will get with the more direct interoperability between Bentley's AEC solutions and ESRI's Arc-GIS," he said.

Such direct connections could prove to be stopgap measures until the OGC and other specifications and standards are fully fleshed out and adopted throughout the GIS and other industries.

However, other potential obstacles block the quick realization of standards-driven interoperability.

Vendors may be drawn by commercial considerations to put their own proprietary interpretations on the standards, limiting the degree of inter- operability among GIS systems, said Allan Levinsohn, an independent consultant and longtime observer of the GIS market.

On a different level, various user organizations will have to overcome their resistance to sharing data, he said.

Even Intergraph Mapping and Geospatial Solutions, another major GIS vendor and one of the leading proponents of OGC's efforts, doesn't see interoperability standards alone as the silver bullet to GIS data-sharing problems.

Matt Tate, director of the company's federal business unit, said that agencies that have put a lot of time and money into building and maintaining a database that is near and dear to a particular set of users will probably be reluctant to let others get their hands on it.

"In a lot of ways it's a cultural thing," Tate said. After putting so much effort into creating that holding, "do they then want to go ahead and expose that data and have other people come in and manipulate it?"

Conversely, he said, Congress is pushing agencies to share more of their data and not waste money by buying duplicate sets of data just for their own use. And agencies are starting to come out with procurements that require vendors to propose solutions that provide OGC standard exchange formats, he said.

But Tate and others agree that it could still be some time before OGC and other interoperability standards take a wide hold in government. Until then, users who operate in the real world will have to find another way to take advantage of GIS data.

Robinson is a freelance journalist based in Portland, Ore. He can be reached at hullite@mindspring.com.